Field Audit Of Performance - Orban OPTIMOD 6200 Operating Manual

4-8
MAINTENANCE

Field Audit of Performance

Required Equipment:
•
Ultra-low distortion sine-wave oscillator/THD analyzer/audio voltmeter
(With verified residual distortion below 0.01%. Sound Technology 1710B;
Audio Precision System One, or similar high-performance system.)
(The NAB Broadcast and Audio System Test CD is an excellent source of
test signals when used with a high-quality CD player.)
•
Spectrum analyzer with tracking generator
(Tektronix 5L4N plug-in with 5111 bistable storage mainframe, or similar.
Alternatively, a sweep generator with 50-15,000Hz logarithmic sweep can
be used with an oscilloscope in X/Y mode, or you can use a computer-
controlled test set like the Audio Precision System One. )
•
Digital voltmeter
Accurate to ±0.1%.
•
Oscilloscope
DC-coupled, triggered sweep, with 5MHz or greater vertical bandwidth.
It is assumed that the technician is thoroughly familiar with the operation of
this equipment.
•
Two 620Ω ±5% resistors.
•
Optional: Audio Precision System 1 (without digital option) or System 2 (for digital
tests).
This procedure is useful for detecting and diagnosing problems with the 6200's perform-
ance. It includes checks of frequency response, noise and distortion performance, and
output level capability.
This performance audit assesses the performance of the analog-to-digital and digital-to-
analog converters and verifies that the digital signal processing section (DSP) is passing
signal correctly. Ordinarily, there is a high probability that the DSP is performing the
dynamic signal processing correctly. There is therefore no need to measure such things
as attack and release times — these are defined by software, and will automatically be
correct if the DSP is otherwise operating normally.
It is often more convenient to make measurements on the bench away from high RF
fields which could affect results. In a high RF field it is, for example, very difficult to
accurately measure the very low THD produced by a properly-operating 6200 at most
frequencies. However, in an emergency situation (and is there any other kind?), it is usu-
ally possible to detect many of the more severe faults which could develop in the 6200
circuitry even in high-RF environments.
Orban Model 6200